Tapping and drilling tool.



J. H. DORMAN. TAPPING AND DRILLING TOOL.

APPLICATION FILED AUG. 1, 1908.

Patented Dec. 14, 1909.

2 SHBBTBBHEET 1.

WITNESSES J. H. DORMAN.

TAPPING AND DRILLING TOOL.

APPLICATION FILED AUG. 1, 1908.

943,009. Patented Dec. 14, 1909.

2 SHEETS-SHEET 2.

' I VE/VTOR "UTT srirrns AT rip.

JOHN H. DORMAN, OF NEW YORK, N. Y.

TAPPING AND DRILLING TOOL.

To all whom it may concern:

Be it known that I, JOHN H. DORMAN, a citizen of the United States of America, residing at New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Tapping and Drilling Tools, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to those attachments for tapping tools or chucks adapted to be applied to the rotating chuck of a drill press for the purpose of providing means whichwill yield and refuse to drive the tap whenever the latter reaches bottom or whenever torsional strain on the tap becomes too great; and my device also relates to superior means for reversing the rotation of the tap in the act of backing it out of the work.

The object of my invention is to provide a tool of this kind which will run smoother, last longer, and be lighter to handle and more easy to take apart and put together whenever repairs or inspection are necessary.

To these ends my invention consists in the peculiar features and combinations of parts more fully described hereinafter and pointed out in the claims.

In the accompanying drawings, Figure 1 represents a side elevation of my complete device, the casing and some of the other parts being shown in section, and the clutch being shown coupled as in tapping adjustment. Figs. 2 and 3 are horizontal sections through the lines 00 m and g 3 respectively, of Fig. 1. Fig. 4 is an external view of my complete device as when used on an ordinary drill press. Fig. 5 is a vertical section through my complete invention. Fig. 6 is a transverse section through the chuck or tool holder. Fig. 7 is a sectional view of the upper end of the chuck spindle showing the mode of attaching the clutchbar. Figs. 8 and 9 are top and sectional views respectively of the clutch -bar detached, and Fig. 10, a top view of a detail showing the upper ends of the two pinion spindles and the manner in which they are locked against rotation.

The friction driving devices and the reversing gears are inclosed within a casing 1, made of aluminum for the sake of lightness, which is a great desideratum in a tool of this character, and I have therefore made all the parts with a View to getting them as Specification of Letters Patent. Patented Dec. 14, 1909.

Application filed August 1, 1908.

Serial No. 446,426.

light as consistent with strength and durability.

2 represents a tapering shank having the usual squared end and adapted to be locked in the chuck 3 and driven by a continuously rotating vertical shaft 4: in the end of the overhanging arm 5 of an ordinary drillpress 6, my device being raised and lowered over a table 7 all of which elements are too well known to need further description.

The gearing is retained within the aluminum casing by a removable base-plate or cover 9 fastened by long screws 10 which enter external longitudinal lugs 11 and provide a strong joint. This cover 9 is made of cast iron in order to receive the bearings for the moving parts centered in it and mounted on it, and it is provided with a circular embossment 9 out on a center coincident with that of the chuck-spindle, and so as to leave in the edge of the cover a circular recess 9' which permits the embossment to fit exactly the interior of the casing, the two being turned from the same center whereby perfect alinement of the parts is assured.

Within the housing, composed of the easing 1 and the removable cover 9, are located three clutch devices, first, a friction clutch adapted to give up under excessive strain, thereby preventing the breakage of slender drills and taps; second, a positive clutch for driving a tap into the work, and third, a positive clutch for backing the tap out of the Work, all of which arrangement is common to the art.

My peculiar friction clutch will first be described. It consists of a circular disk 12 formed integral with a hollow elongated vertical shaft 13 which extends up through the longitudinal center of the device, termis nating flush with the top of the casing 1, where it is connected by a screw 14 to the driving shank 2. This shaft 13 is surrounded by a friction sleeve or bushing 15 having an integral circular flange 16 at its lower end adapted to engage a corresponding shoulder 17 formed on the inside of the casing. This bushing 15 is preferably made of phosphor bronze to withstand the wear of the revolving hollow shaft 13. The shank 2 is provided with a circular, horizontal collar 18 which overlaps and bears upon the end of the friction sleeve 15 for the purpose of preventing the screw 14 of the shank 2 from unscrewing prematurely.

When the shaft 4 ofthe continuously driven drill-press is set in motion, it also drives the shank 2 continuously, and in one direction, which shank in turn drives the hollow shaft 13, and the latter drives 'the drill or tap which operates upon any suitable piece of metal work held upon the table of the drill press. The intermediate mechanism by which the chuck is driven consists of a comparatively large, horizontal gear 19 clutched to turn with the hollow drive shaft 13 by means of a circular nut 20 surrounding the lower portion of said shaft at a point a short distance above the friction disk 12. This nut 20 has a left-hand screw thread to engage that on the shaft, and when screwed down clamps a central web 21 of the gear 19 so that the two Will revolve together. Washers 22 and 23 of vulcanized fiber or other suitable material are interposed between the parts to take up wear and to increase friction. A set screw 25 is employed to lock the nut 20 at any desired point of adjustment. The nut may be adjusted from the outside of the casing by inserting a tool 26, shown in dotted lines, through a recess or hole 27 in the casingint-o the radial hole 24, thereby locking the two parts together. hen the nut and casing are thus locked together, the casing should be turned bodily while the shank 3 is held against turning, whereby the nut will tighten or loosen to increase or diminish the driving friction between the drive shaft 13 and the gear 19. The revolution of gear 19, when the clutch is in, actuates a revers ing gear 28 through the medium of three intermediate smaller gears 30, 31 and 32, centered to revolve on two vertical fixed shafts 33 and 34 in an offset of the casing 1. From the adjacent faces of these two larger gears 19 and 28 project four short cylindrically shaped clutching lugs 38 and 39, two on each gear. These clutch lugs are adapted to be alternately engaged, for driving or reversing the tap, by a transverse clutch-bar 36 which passes loosely through the chuck-spindle 29 around which said larger gears 19 and 28 revolve. The chuckspindle 29 has an endwise movement in its housing, the play of which is limited by the clutch-bar 36 coming in contact respectively with the upper and lower gears 19 and 28. This bar also prevents the spindle from dropping out.

The chuck-spindle 29 drops down into extended position by its own gravity. hen the whole tool is lowered and the tap comes in contact with the work below, said spindle is pushed up into the housing until the clutch bar 36 engages the sides of the lugs 38 on the upper gear 19 and the bar and gear will revolve together to operate the tap. As this clutch-bar 36 is slightly loose in the spindle, its opposite arms will accomboth lugs 38 to drive the spindle.

modate themselves with equal pressure on.

The underside of the clutch-bar is recessed longitudinally to retain the bar, as shown in dotted lines in Fig. 7. The clutch-bar also has slight endwise play. The additional means for accomplishing this triple movement of the clutch-bar consist of a round locking and pivoting pin 39, rounded at both ends, and contained within a longitudinal bore 40 intersecting the transverse slot 41 in the spindle and extending therefrom to the upper end of the spindle. The bore is considerably larger than the diameter of the round pin in order to allow the lower end of the pin to move laterally with slight longitudinal movements of the clutch-bar 36. The clutch-bar is loosely and pivotally held at the middle by this pin, and cannot get out of its slot because of the shoulders 42 which come in contact with the lower edges of the clutch-bar recess 41. A shallow recess 43 is cut into the spindle at the upper and lower edges of the recess 41 to give the shoulders on the clutch-bar a better bearing surface. The round clutch-bar locking pin is held within the central bore 40 by a longitudinal screw 44 in the reduced upper end of the chuck-spindle.

The lower face of the friction disk 12 of the hollow driving shaft 13 is recessed around its central bore which contains the reduced end of the spindle 29, to receive the shoulder of the thicker lower portion of said spindle, a space 45 being left between these parts so that the shoulder will not come in frictional contact therewith.

All of the gears revolve while the chuckspindle is coupled with either the upper driving gear 19 or the lower reversing gear 28.

The reversing movement of the spindle to back the tap out of the work is effected by lifting the housing bodily upward a short distance, while the tool is in the work, until the clutch-bar 36 clutches the upwardly pro jecting lugs 39 on the reversing gear 28, which is all the while revolving in a direc-' tion opposite to the driving gear 19 above. In most of the tapping tools of this kind, the pulling out of the driving clutch is ac companied by much grinding and friction, which I have overcome by the devices now to be described. These devices consist of concaved seats 46 formed in opposite sides of the arms of the clutch-bar 36 to receive the convex and tapering surfaces of the two clutch-pins 38 on the driving gear. These seats extend from the top of the clutch-bar downward a distance a little greater than the length of the clutch-pins 38, as seen in Fig. 1, and have the general shape of the segment of a truncated cone. These seat formations result in allowing the bar to slide down and off the pins with greater smoothness, reduced noise and shock, and thereby make the whole attachment much more comfortable to use, and also much more durable. The frictional surfaces might be slightly changed in form and shape without departing from the scope of my invention.

The sides of the clutch-bar which engage with the locking lugs 39 on the top of the reversing gear are not recessed because the frictional pressure on them is immaterial. It is desirable and necessary to prevent the reversing gear 28 from moving up with the spindle, and this I accomplish by forming a recessed hub 47 on the bottom of the reversing gear. This hub drops into a countersunk annular recess 4L9 in the top of baseplate 9. Horizontal retaining plates 48 enter the recess 49 in the hub and anchor it to the base-plate. These plates lie in transverse recesses 50 so that their upper surfaces are flush with the top of the base-plate 9, in which position they are held by screws 51.

The chuck or tool holder on the lower end of the spindle 29 is secured thereto by a foot 66, clamping plate 72 and screws 73. As a further precaution against turning on the spindle, the bottom of the foot is provided with dowels 7a which enter corresponding holes in the chuck head 57. A floating block 53, having rectangular flat or squared sides, is located in a transverse recess 54 in the chuck head, and is adapted to have a free sliding movement across the axis of the spindle 29, being retained against sliding out by a screw 55 and slot 56, (Figs. 5 and 6). Cotiperating with the chuck head 57 is an axial guiding and centering. recess 58 in the spindle, preferably conical in shape, and the upper end 59 of this recess, where the latter comes to a point, is tapered to receive and center the butt end of the shank of a boring or tapping tool, such as shown in dotted lines in Fig. 5.

The floating block 53 is provided with a vertical V-socket 60 arranged to be drawn by a set-screw 61 to a central position rela tive to the vertical axis of the centering recess 58, so that after the end 59 of said tap has first been introduced into the centering recess 58, the tightening of the set-screw will bring the tap up into perfect aline ment. This set-screw is threaded externally from end to end and operates in a removable plate 62 which covers the larger side of the V-socket. An extension 63 on the outside of the plate provides a longer barrel for the set-screw to operate in and materially assists in keeping it from unscrewing. A polygonal flush socket 64; in the outer end of the set screw is made to receive the squared end of an L-wrench by means of which the screw is worked. The removable plate 62 is secured to the floating block 53 by four screws 65. When the shank of a cutting tool is passed up into the central recess of the chuck its end will come in contact with the conical wall of the end thereof and. be guided to the true center of the spindle. The tool however will not assume a true alinement throughout until the set screw 61 is tightened. The tightening or screwing up of the latter, when the tap is held tightly in the conical recess, draws the floating block and the vertical walls of the V-socket and shank of the tool up in true alinement and centers the tool perfectly, in which adjustment it is shown in dotted lines in Fig. 5.

The means for locking the shafts 33 and 3% of the small intermediate gears of the reversing mechanism consists of a short large-headed screw 67 which overlaps the ends of the spindles and fits in segmental recesses 68 therein as seen more clearly in Fig. 10.

The casing 1 is locked against rotation while the tool is at work by a laterally extending arm 69 adapted to be removably screwed by hand into the side of the casing. A vertical stop. arm (not shown) may be used in a vertical socket 70 to regulate the depth of the tapping.

To hold the hollow shaft 13 rigid while the shank 7 is being screwed up or unscrewed, coinciding holes 71 are made through the casing l, bushing 15, and hollow shaft. The insertion of a pin through these holes lock all three parts together.

Briefly described, the operation of my device is as follows: The shank 2 having first been locked in the chuck 3 of the drill press and the mechanism set in motion, the whole attachment is lowered to the work on the table below by means of the hand lever 4 until the tap strikes the work, whereupon the attachment, excepting the spindle 29, will continue to descend until the clutch-bar will have been raised sufficiently to clutch the driving gear 19, which has all the while been idly revolving, and the tap will be forced into the work. When the hole has been tapped to the proper depth, the tap can be backed out by lifting up the lever 4t and raising the tool. The tap being still in the work will hold the spindle down until the clutchbar 36 slips off the lugs 38, and onto the lower lugs 39 of the reversing gear 28 which, rotating in the opposite direction, backs the tap out of the work. It will be seen that in the event of the excessive strain upon the tap, the upper friction clutch will be overcome and the driving cease. To release the spindle from the reversing clutch the operator raises shaft 4 of the machine and reverses the machinery, sliding the clutch-bar 36 off the lower lugs.

It is evident that my device may be varied in many ways that might suggest themselves to those skilled in the art, without departing from the scope and spirit of my invention, and I wish it understood that I do not limit myself to the exact construction herein shown but consider myself entitled to all such variations.

Having thus described my invention,what I claim as new and desire to secure by Letters Patent, is:

1. In a tapping attachment for drill presses, the combination with a casing containing driving and reversing gears and provided with means for holding it against rotation, of a chuck-spindle having a longitudinal recess, a pivotal retaining pin therein, a transverse clutch-bar loosely held by the pin in said spindle recess, retaining shoulders on said bar, and oppositely projecting pins L1 3011 the driving and reverse gears adapte to be alternately engaged by the bar.

2. In a tapping tool, a clutch-bar pro vided with transverse concaved tapering recesses in.its opposite ends, in combination with a perforated chuck-spindle in which the bar is loosely held, and driving and reversing mechanism provided with convex tapering lugs adapted to fit and slide in and out of said recesses and to equalize the lateral strain on said bar in the coupling and uncoupling operations.

3. In a tapping tool, the combination with a spindle provided with a longitudinal bore in its upper end intersecting atransverse hole, a clutch bar loosely held in the transverse hole, a retaining screw at the upper end of said longitudinal hole, and a pin interposed between the screw and bar and loosely fitting in said bore, whereby the bar is allowed slight endwise play in said spindle, and whereby the pin has sidewise play to move with the bar.

4. A tapping tool or attachment provided ;with a recessed casing inclosing a frictiondriven spindle and adjustable friction devices, in combination with a friction regulating nut having holes in its periphery reg- 5 istering with the recess in the casing, wheref by a temporary bar can be removably inserted and the friction devices thereby regulated from the outside of the casing. I 5. In a tapping attachment, a housing I having an offset provided with intermediate reversing gears two parallel shafts-set in the housing, and on which said gears are centered, said shafts being provided with eX- ternal segmental recesses, and an interme I diate locking screw having a circular head, the opposite sides of which intersect the circumferences of the shafts and fit into said recesses.

6. I11 a reversible tapping tool, the combination with a driven spindle, of a transverse loose clutch bar passing through the spindle, a longitudinal loose retaining pin in the spindle, and means for holding the pin in lace.

7. In a tapping tool, the combination with a driven spindle, a shank therefor screwed in the top thereof, a bushing for the spindle, a housing or casing for the bushing, and registering transverse perforations in the spindle, bushing, and easing, whereby a locking pin can be inserted to hold said parts against turning while the shank is being screwed in or out of the spindle.

In testimony whereof, I afli-X my signature in presence of two witnesses.

JOHN H. DORMAN.

lfVitnesses G. B. 'Sonnonnnn, J EANNETTE $101211. 

